The present invention is directed to a device and process for the continuous mixing of substances, and particularly plastics, wherein the products which are to be mixed may be in powder, granule or liquid form. The products which are to be mixed are continuously introduced into the mixer, and the finished, mixed product is continuously removed from the mixer.
Continuous mixers are known to the art, in various embodiments. The state of the mixing art is illustrated by German Pat. Nos. 1,188,264; 1,193,016; 1,244,723 and 1,679,865, and German published Patent Application No. 1,778,436.
A continuously operating mixer offers the advantage that it can be installed immediately before a processing device, such as an extruder or calendering rolls, so that the mixed product can be directly brought in the mixer to the desired processing temperature, and thereby obviate the need for intermediate heating between the mixer and the processing device. With such a continuous mixing process, the prior art has at times encountered problems in obtaining a uniformly and intensively mixed material, and also in particular in ensuring a uniform heat distribution within the mixer, so as to avoid the formation of heat pockets. To overcome these problems, a variety of attempts have been made by the prior art to conduct the materials being introduced as directly as possible to the mixing blades, or to premix the material being mixed with the aid of separately installed mixing devices, as described in the abovementioned German Pat. No. 1,118,264.